This disclosure relates generally to a slider suspension system for a semi-trailer, and more particularly to the wear pads installed between a sub-frame member of the slider suspension system and a guide rail of the semi-trailer.
Conventional semi-trailers of the type hauled over the road by trucks connect to the truck at a hitch or fifth wheel, and include a suspension system, typically having a pair or multiple pairs of parallel axles. In many semi-trailers, the suspension system is slidable forward and backward relative to the trailer for adjusting the load on the rear axle or axles.
A slider frame can be moved forwardly or rearwardly in relation to the tractor rear axles in order to adjust the load carrying capacity of the semi-trailer while complying with roadway weight laws. The ability to move the suspension system relative to the cargo containing portion of the semi-trailer is desirable for a number of reasons. When a tractor and semi-trailer must maneuver around city streets, relatively tight corners are common. By moving the suspension system forward, it is easier to negotiate tight corners. In contrast, when traveling on highways, moving the suspension system to the rear of the cargo container puts a larger percentage of the load on the axles of the tractor, providing a better ride.
In order to lock the position of the suspension system relative to the trailer, conventional systems include retractable pins. The pins extend through apertures in a member of the slider suspension system, typically a sub-frame member, and also extend through aligned apertures in a guide rail of the trailer. The pins are retractable to allow the position of the suspension system to change relative to the trailer. Once the desired position of the suspension system is obtained, the pins are lockingly inserted though the apertures of both the sub-frame member and the guide rail.
In conventional slider suspension systems, a wear pad is often installed between each sub-frame member and an associated guide rail. The wear pad is a planar wear resistant, low friction pad disposed between the top surface of each sub-frame member and the sliding underside surface of the guide rail.
While these wear pads provide some protection to the surfaces of the two structural members, conventional wear pads do not protect the outboard surfaces of the sub-frame and the sliding inboard surfaces of the guide rail. The lack of any protection between these two moving surfaces creates wear, friction, and noise.
Additionally, some sub-frames of the slider suspension system are made from aluminum in order to lower the weight of system. The guide rails of the semi-trailer are typically steel. When the surfaces of these two different members are exposed to water, galvanic corrosion is created on the aluminum sub-frame members.
Furthermore, there are two industry standards for the guide rails for trailers, each with a different width. This results in a need for spacers to be used with conventional wear pads to accommodate the different widths of the different guide rails for trailers.
Moreover, in conventional slider suspension systems, the wear pads are typically fastened to the sub-frame using set screws or other fasteners, such as self-tapping screws, or with slot or plug welds. These types of installation and attachment systems require excessive labor.
Accordingly, there is a need for developing an improved wear pad that addresses one or more of the above-identified drawbacks.